The backrest of a vehicle seat is provided with a headrest on its top. The headrest supports the head of an occupant from the rear. At a rear-end collision by another vehicle, the headrest receives the head of the occupant to cushion the impact on the neck region of the occupant.
While an occupant is seated on a vehicle seat, the occupant often leans the upper body against the backrest with the head slightly spaced apart from the headrest. At a rear-end collision by another vehicle, the head of the occupant is received by the headrest while slightly inclined backward and then tilted forward by the reaction of the impact force. This impairs the advantageous effects of the headrest, i.e., shock-absorbing advantageous effects on the neck of the occupant.
Technology has been developed that allows the headrest to receive the head of an occupant rapidly by letting the upper body of the occupant deeply sink into the backrest of a vehicle seat at a rear-end collision by another vehicle (See PTL 1). More specifically, a pressure receiving member is provided within the frame of a backrest such that the pressure receiving member is movable in the front-back direction. At least the front surface of the frame and the pressure receiving member is covered with a cushion pad (See PTL 1). In the technology disclosed in PTL 1, at a rear-end collision by another vehicle, the upper body of the occupant sinks into the cushion pad and the central portion of the cushion pad and the pressure receiving member retreat, thus allowing the headrest to rapidly receive the head of the occupant.
In the technology disclosed in PTL 2, an upper coupling wire is bridging the upper portions of the left and right side frames of the backrest. The lower coupling wire is bridging the lower portions of the left and right side frames. A plate-like pressure receiving member is coupled to the left and right side frames via the coupling wires and disposed between the left and right side frames to support the backrest pad from the rear.
In the technology disclosed in PTL 3, multiple springs are fixed to the backrest frame such that they extend across the lateral width. A support material is mounted in front of the springs. An airbag is mounted in front of the support material. The inflation or deflation of the airbag changes the shape of a pad disposed in front of the airbag. This operation can adjust the lumbar support position of an occupant.
The side frames of the backrest disclosed in PTL 1 are each provided with a reinforcing cloth attaching member (reinforcing cloth fixing bracket). The reinforcing cloth attaching members are disposed around the pressure receiving member. The reinforcing cloth attaching members are connected with a reinforcing cloth to control the direction of deploying the airbag.
In the technology disclosed in PTL 4, a hook and an airbag module are mounted on the side frames of the backrest. A reinforcing cloth is stretched from the hook to a skin seam via the vicinity of the airbag module. At the inflation of an airbag in the airbag module, the airbag is guided to the seam by the reinforcing cloth. Further pulling of the reinforcing cloth by the inflating airbag causes the skin seam to be torn and the air bag to protrude from the torn seam (See PTL 4).
In the technology disclosed in PTL 5, a vibration generator that generates vibrations is disposed within the backrest. The vibration of the seat back by the vibration generator can provide the occupant with massage and awakening effects.